These words are applied to persons who exhibit more than average acquired or native skill in the performance of some act or operation. Competent attributes to the subject the ability to carry out the requirements of a specific task. By implication, the completed task is one that can be rated objectively as being either satisfactory or unsatisfactory: No competent tax accountant could possibly have made such egregious errors in making out your return. Thus, while competent can suggest expertise in a complicated field, adequacy rather than excellence may be indicated by the word. A performing artist, for example, might be insulted if described by this word: competent piano-playing that nevertheless lacked inspiration and nuance.

Able and capable at their most neutral may indicate the practicable or possible: an infant barely able to walk. Capable is stronger here in indicating potential, possibly unsuspected, whether for good or ill: a husband capable of more tenderness than his wife had ever allowed him to express; totalitarian governments capable of the most unspeakable enormities. Where the words approach competent in referring to above-average skill, able suggests versatility and resourcefulness and capable a practical, problem-solving approach: an able architect; a capable stenographer. Capable stresses trained proficiency for a specific task, whereas able suggests a wider perspective or potential: capable lawyers, well-schooled in the intricacies of company law; able children, eager for knowledge, though thwarted by a lack of training in the fundamentals of reading. Also, capable can be applied to things as well as animals: an electronic computer capable of storing millions of bits of information; a shipyard capable of producing two nuclear submarines a month. Able , on the other hand, applies only to creatures capable of performing an action.

Qualified stresses the possession of required skills and is generally applied to professions or trades for which a minimum of schooling or training is required. A qualified teacher has completed the academic training prescribed, but is not necessarily competent .

Efficient adds to competent the idea of a skill in making the most of the time and material available. A mechanic who is competent and efficient will perform a repair job more quickly and cheaply than a mechanic who is merely competent .

Fit and good are general words often used in place of the other words in this list. Fit is usually used predicatively: the manager is not fit for his position (meaning not qualified , not competent , not efficient ). The specific meaning of good, when used in this sense, is indicated by the context. A good teacher is both qualified and competent ; a good manager is both competent and efficient .